Radio lead sight



March 1, 1955 e. E. WHITE 2,703,039

RADIO LEAD SIGHT Filed March 11, 1943 2 Sheets-Sheet 1 A Q} N N I INVENTOR a 61/2 ford E. WWW/be BY E fATTORNEY March 1, 1955 Filed March 11, 1943 G. E. WHITE RADIO LEAD SIGHT 2 Sheets-Sheet 2 INVENTOR Gifford E. W2 fie ATTORNEY United States Patent 9 F RADIO LEAD SIGHT Gifford E. White, Hempstead, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Application March 11, 1943, Serial No. 478,807

12 Claims. (Cl. 89-41) My invention relates to gun sights and concerns particularly lead sights adaptedfor a radio line of sight.

It is an object of my invention to provide a computing gun sight in which the line of sight may be maintained regardless of haze or other conditions atfecting'visibility.

A further object of my invention is to provide an attachment for optical gun sights to permit orienting'a gun by following a radio line of sight. 7

Still another object of my invention is to provide a radio line of sight for local-turret fire control systems.

It is also an object of my invention to operate a lead sight by radio.

Other objects and advantages will become apparent as the description proceeds.

In accordance with my invention in its preferred form, I employ the elements of an optical lead sight andcornbine therewith an automatic target tracker operating by means of high frequency radio waves. The optical sight is provided with computingmechanism so arranged that it is driven by the motion of the gun'so as to set back the line of sight, whereby the'requisite lead is-introducedin the gun position when the-line of sight'is on the target. The line of sight is toward a so-called present position of a moving target, whereas the gun must be oriented to fire toward the position which will havebeen reached by the target when the projectile strikes. In order to produce indications or shaft positions corresponding to the'present position of the target in elevation and azimuth for correlation with the radio tracker, which has a line of sight in the present position, I provide pick-offs on the mechanism of the optical sight normally utilized to determine the positions of the optical'elements; The angular positions of these optical elements represent the correction from gun position required to. produce the line of sight to present position of the target. These corrections-values are combined with the gun'positions in order to produce indications or shaft rotations representing the angles of the computer line of sight in azimuth and elevation. Present position indications may be transmitted electrically to the radio tracker control andcompared therewith electrically to enable a gunner to determine whether or not the gun is correctly oriented.

A better understanding of the invention will beafforded by the following detailed description considered in connection with the accompanying drawing, and those features of the invention which are believed to benovel and patentable willbe pointed out'in the claims appended hereto.

In the drawings,

Fig. 1 is a schematic diagram of one embodiment of my invention, and

Fig. 2 is a perspective view of a portion of the apparatus including the gun turret and mechanism mounted therein.

Like reference characters are utilized'throughout the drawings to designate like parts.

In Fig. 2 a revolving gun turret such as may be used on aircraft is shown fragmentarily for illustrating the application of my invention to local turret systems. The turret is represented as being of the upper local turret type for mounting a machine gun 11" and housing both the mechanical equipment and the gunner who operates the mechanism. There is a hemispherical'top shell represented by broken hne 12 with an opening 13 therein for the barrel of the machine gun 11; The entire turret is rotatably mounted and is represented as'b'eingcarriedib'y a ring 14 which isrotatably supported. by-rneansof: roller 2,703,039 Patented Mar. 1, 1955 ice bearings 15'on a ring plate 16 which is rigidly secured to the fuselage of the aircraft (not shown). The plate. 16 is toothed on the under side to form a ring gear. The rotation of the ring 14 represents the angular rotation of the gun 11 in azimuth. To permit varying the elevation of the gun, it is mounted on trunnions providing rotation about a normally horizontal axis 17, movement about whichlrepresents the angular position and elevation of the gun 1 Within the local turret there is also a box 18 for housing driving motors and control equipment. A computer case'19 is mounted directly upon the gun 11 at the breech end thereof. For operation of the control and driving mechanism, control handles 21 are mounted at or near the gun breech. The computer case 19" carries optical sights 22 for use when the target is to be tracked optically. Suitable deviation indicators such as a cross-pointer'instrument 23 are provided for use when the target is tracked by radio. The gunners position is within the turret behind the control handles 21 which enable him to effect suitable operation of the mechanism within the motor control box 18 for orienting the gun 11' both in azimuth and elevation; For eifecting azimuth orientation of the entire'turret, including the gun 11, a pinion 20 is provided which meshes with the ringgear 16 and is driven bymechanism (not shown) within the box 18. Forsetting the gun elevation there is a sector gear 10 secured to'the trunnion 17, and: apinion 9,1'neshing with theis'ectjor 10 and driven by mechanism (not shown) within the The mechanism within the computer case 19 of Fig.) 2 is representedschematically in Fig. 1 to the right'of the dashed line 24;

For tracking thetarget with aradio line of sightgan automatic tracker 25 is shown in Fig. 1 which maybe mounted in" any suitable portion of the aircraft remote from the'turret represented'in Fig. 2. Inte'rco'nnectih'g the turret and the tracker 25, suitable electricalconnections are provided, represented in Fig. 2 by a cable- 26 which includes the groups of conductors 27 and zslFig. 1) for transmitting present positions in azimuth and elevation, respectively, and the schematically represented cable 29 for-transmitting range indications.

The radio tracker 25'may be of any desired type, and it is represented in simplified form as being of the spinning-scanner type described in the copending application Serial No.- 441,188, of Holschuh, Gifford] E. White, Mieher, and Shepherd, filed April 20, 1942 a1'1d\\'/hi ch maturedinto U. S. Pat-entNo'. 2,617,982. Such a radio tracking system comprises a scanner or' radiator 30, a

' movable head- 31'for supporting the radiator 30; and

means for varying'theposition of the head 31' to orient the radiator in azimuth andelevation. The radiator 30 is shownas being of the parabola type including a dipole antenna 32; The head 31 contains mechanism (not visible) for rotating the'radiator 30 about a spin axis 33, which is also the-radio line of sight.

For permitting variation of *the elevation of the radio line of sight'33, the head is provided with trunnions represented-by a horizontal or trunnion axis 34,mounted in-stanchions 35. For permitting orientation in azimuth, the stanchions 35 are secured to' a turn table 36; shown withia toothed periphery to form a gear, rotatableabout a vertical axis 37.

There is-a radio transmitter (not shown) coupled to the antenna 32 and there is a radio receiving equipment including various stages designated'by therectangle'3'8.

For producing the requisite motion of the scanner 30 in'azimuth andelevation, suitable motive means and control devices are provided which are designated col lectively as the scanner control, represented by a rectangle 39. There is a high frequency radio channel from the dipole antenna 32 to the radio receiver 38, the channel being represented schematically by the conductor pair 41L There is an electrical connection by means of' a; cable represented by the line 42 from the output of the radio receiver 38 into the scanner control 39. The arrangement is such that a-microwave or high-frequency radio beam projected by the radiator 30 toward'a target is reflected back from the target and picked up by the dipole antenna 32- for actuating. the radio receiver 38 mdicator or an electrical indicator.

which in turn regulates the scanner control 39 for an indication of the range of the target in the form of an electrical voltage, supplied through the cable 29, the voltage having a magnitude proportional to the range.

The scanner control mechanism 39 is provided with a pair of indicating shafts 49 and 51, the angular positions of which represent the angular positions of the scanner head 31, and therefore the target, in azimuth and elevation, respectively. For enabling the gunner to compare the actual radio line of sight of the target represented by the angular positions of the shafts 49 and 51 with the hypothetical line of sight determined by the computer from the actual gun position, the deviation indicator 23 is provided. The latter may be of any suit able type such as a cathode ray indicator, a mechanical It is shown as an electrical indicator of the crossed-pointer type.

The computing mechanism shown in Fig. 1 is of the mechanical type employing cams and differentials as in certam standard forms of optical computing sights. For simplicity the windage corrections have been omitted, but the computing mechanism is otherwise similar to that described in the copending application Serial No. 358,382 of Holschuh and Vielehr, filed September 26, 1940 and which matured into U. S. Patent No. 2,396,701. In addition to the mechanism ordinarily provided in a purely optical computing sight, however, I provide also arange servo or motor 53 for converting an electrical indication of range to an angular mechanical motion for indication of range, and I provide a three-dimensional cam mechanism 54 to introduce the correction factor necessitated by the fact that the optical line of sight is on a slanting azimuth plane, Whereas the radio line of sight is with respect to a horizontal azimuth plane. Low-friction pickoif mechanisms are also provided for transferring indications of the correction angles computed by the computmg mechanism. These pick-oif devices are represented as being of the electrical type including an azimuth pick-off mechanism 55 and a schematically represented elevation pick-off mechanism 56.

e computing mechanism mounted Within the computer case 19 (Fig. 2) is provided with two input shafts 57 and 58 (Fig. 1), representing gun positions in azimuth and elevation, the angular positions being transmitted to the shafts 57 and 58 through flexible shafts59 and 61 shown in Fig. 2. For use when the target is to be tracked optically, there is a suitable reflector 62 rotatable about a horizontal or elevation axis and a second reflector, 63 which may take the form of a half silvered prisrn'or mlrror, rotatable about the slant azimuth plane of the gun 11. It will be understood that the optical line of sight is along the line 64 and that an image of a reticle 65, illuminated by a lamp 65', is reflected by the mirror 62 and the reflecting surface of the prism 63 into the eye of an observer. The reticle image thus appears together with the image of the target coming from the line of sight 64. When error in the sighting is corrected by movement of the gun and therefore by rotation of the shafts 57 and 58 to bring the image of the target and the image of the reticle in alignment, the setting of the sight, 1. e., the apparent position of the reticle, is adusted or corrected for compensation of the change in posltlon of the gun and any change in speed of the target. The apparent position of the reticle is determined by the angular settings of the reflectors 62 and 63. The mirror 62 is adjusted through gearing 66 by rotation of an elevation connection shaft 67, likewise, the deflector 63 is adjusted through bevel gearing 68 by rotation of an azimuth correction shaft 69.

The angular positions of the shafts 67 and 69 represent the necessary corrections in the line of sight to cause the projectile to strike the target. Mechanism is shown only for introducing corrections due to angular rate of elevation and azimuth and the gravity effect. It will be understood, however, that my invention is not limited to the simplified form of computer shown for convenience and embraces the control of the radio line of sight by means of total correction indications taken from the optical-hne-of-sight correction-indicating shafts 67 and 69 by v aroaosa i r means of pick-offs such as the pick-offs 55 and 56 regardless of the number of factors entered intothe computation. r.

In the simplified computer shown there is mechanism 71 for inserting the prediction angle due to the rate of motion of the target in elevation and mechanism '72 for making the ballistic correction due to gravity.

There is mechanism 73 for inserting the prediction angle due to the rate of motion of the target in azimuth.

An optical computing sight of previously known type may be provided with a stadia mechanism for computing range optically, or other means may be provided for producing an angular rotation proportional to the range of the target. Such means are represented schematically in the present application by a handwheel 74 geared to a shaft 75, the angular position of which represents range. In accordance with my invention, however, the range shaft 75 is coupled to the range servo 53 for inserting range electrically. For example, bevel gearing 76 may be interposed between the range shaft 75 and the mechanical output of the range servo 53.

In an optical sight the computing mechanism and the sights are mounted on the gun so that the rotation of the sights in azimuth is around a great circle in a slanting plane, whereas the angular position of the gun taken from the shaft 57 is with respect to a horizontal plane. To correct for this factor, the azimuth rate computing mechanism 73 is driven by the gun azimuth shaft 57 through a change-speed transmission varying in accordance with the cosine of the elevation. The cosine factor is introduced by means of a helical cosine cam 77 driven by the gun elevation shaft 58. For introducing the cosine factor into the azimuth rate, a ball carriage mechanism 78 is provided. This comprises a disc 79 driven by the azimuth shaft 57 through bevel gearing 81, a ball carriage 82, a cam follower 83 adjusting the position of the ball carriage 82, and a cylinder 84 driven by the disc 79 through the ball carriage 82 at a speed determined by the speed of the azimuth shaft 57 and the radial position of the ball carriage 82 with respect to the rotating disc 79.

It will be understood that if the apparatus is to be used exclusively with a radio line of sight, one may omit both the cosine factor change speed mechanism consisting of the elements 77, '82, 84, and 79, and the sccant factor mechanism 54.

For introducing the effect of time of flight of a projectile in the rate predictions, time-of-flight mechanism 85 is provided, comprising a constant speed motor 86 rotating a disc 87, a cylinder 88, and a ball carriage 89 interposed between the disc 87 and the cylinder 88. For positioning the ball carriage 89, a cam follower 91 is provided which cooperates with a cam 90 which is driven by the range shaft 75 and is so shaped as to produce motion of the cam follower 91 inversely proportional to the time of flight,t, which is an increasing function of range.

The azimuth rate predicting device 73 is so arranged as to multiply the time of flight by the corrected speed or gun rotation in azimuth represented by the rotation of the cylinder 84. Accordingly, the mechanism 73 comprises a cam 92 and cam follower 93 cooperating therewith, a ball carriage 94 adjusted in position by the cam follower 93, a driven cylinder 95, a driving disc 96, and a differential 97. Thediflerential 97 includes an input shaft connected to the cylinder 84, a second input shaft connected to the cylinder 95, and an output shaft 98 connected to the cam 92. The arrangement is such that in case of any difference in angular speed between the cylinders 84 and 95, shaft 98 will be rotated in one direction or another to carry the ball carriage 94 in such a direc tion as to change the speed ratio in the transmission from the driving disc 96 to the driven cylinder 95. Thus, the angular position of the cam 92, and therefore of the shaft 98 depends upon the speed ratio of the cylinder 84 and the disc 96. The speed of the disc 96, however, is inversely proportional to the time of flight so that the angular position of the shaft 98 indicates the product of the time of flight and the speed of the cylinder 84, which latter is the corrected azimuth angular rate of the gun. The shaft 98 is connected to the azimuth correction shaft 69 through bevel gearing 99 so that the angular position of the shaft 69 represents the requisite corrections in the optical line of sight.

In a similar manner the elevation rate mechanism 71 entrance produces angular'position: ofanuoutput shaft: 101': which is the product of: the ti'tnerofsfli'ght' and: the 1 speed of retation of a shaft 102, which is' drivenrb'yuhe elevation shaft 58 through a bevel gear 103;" Itwill be: observed that the mechanism 71 is provided with adriving-disc 104 driven by the time-of-fiight cylinder- 88 correspond ing to the disc 96, and a diiferentiah 105 which compares the speed of the input shaft 102* with the speed of an input shaft 106 driven by the'disc'104 through. aball carriage corresponding to that shown in the: mechanism 73.

The mechanism 72- for introducing the ballistic colrection in elevation comprises athree-dimensional cam 107 having a lift which-varies axially 'in accordance with the cosine law. The cam 107 has a lift which varies with angular rotation in accordance with the gravity function of range. For moving the cam 107 axiallyin accordance with variations in gunelevation, a rack and gear mechanism 108 is provided, and for rotating the cam 107 in accordance with range a gear 109 isprovided meshing-with a long pinion 111 driven-by the range shaft 75. The ballistic correction is represented by the lift of the cam follower 112 which istoothed' to form a rack meshing a pinion 113 on a shaft- 114. For combining the rotations of the shaft 114 and 101, a differential 115 is provided having an output gear 116 coupled through a bevel gear 117 to the elevation correction shaft 67.

As already explained, indications of the angular positions of the shafts 67 and 98 are'picked'offthrough electrical pick-ofis 56 and 55.

Owing to the fact that the rotation of the azimuth correction shaft 69 has been converted into terms of the slant plane for the'optical line of sight, it is necessary to reconvert the angular indication of the pick=offinto terms of a horizontal azimuth plane for use with the radio tracker 25. This is accomplished" by means of the compensating mechanism 54 which'introduces asecant function into the angular indication of azimuth correction. For transmitting the angular rotation of the azimuth correction shaft 98 tothe compensationdevice'54, an electrical transmission system is provided'comprising a transmitter or pick-off SSand' a receiver 117. The pickoff 55 may constitute mechanism of the type use'd' in selfsynchronous remote position indicators such as Selsyn systems, for example. Preferably, however, it isso constructed as to provide a very light frictional load for the shaft 98. It may be of the type having jewelbearings such as used in Tel'egon"transmitters, for-example. As represented schematically, the pick off55 comprises a rotatable armature winding 1'18" mounted on "a shaft 119, geared to the shaft 98, and a polyphase stationary winding 121. For energizing the armature 118, a source of single-phase alternating current '22-is provided; This may be of any suitable frequency, depending uponthe design of the apparatus, e. g. 400-cycl'e current which is generally available on aircraft. The receiver'117 may be similar in construction to the transmitter 55 includ ing a polyphase stator 123 and a single-phaserotor 124'. Although the rotor 124' may be energized by a singlephase current synchronous with the source'122 inorder to reproduce the angular position of the rotor 118, in order to minimize-the load on'th'e system, I prefer to utilize a servo mechanism. In case a servo mechanism is used, I employ the rotorwindin'g 124' merely as an indicator of angular coincidencebetween the angular positions of the shaft 119 and the shaft 125carrying the rotor 124. For this purpose aphase sensitive amplifier shown within the rectangle 126 isprovided which is energized by a source of single-phase current preferably, the same source 122 which energizes the'rotor 118. The amplifier 126 is arranged-to produce aidirect current out put at conductors 127 in the event of any deviation from a quadrature relationship between the electrical angles of the rotors 118 and'124i- The phase-sensitive amplifier 126, herein shown as a rectifier, comprises an input transformer 128 and a primary winding 129 connected to the receiver rotor winding 124, a center tapped secondary winding 131, a pair of asymmetrical elements such as vacuum tubes with a separate plate voltage supply or, as shown, simply rectifiers 132 and 133 of the diode type, for example, and a center leg transformer 134 having a primary winding 135 connected to the source; 122 and a secondary winding 136. The diodes 132 and--133have'anodes connected to the ends of the transformerwinding;131 and"catho'des connected to the output conductors 127. Two resistors 137 are connected in series between the cathodes of the diodes 132 and 133 and have a junction terminal1-38. The secondary winding 136 of the center leg transformer 134 is connected between the mid-terminal 139 of the transformer winding 131 and the resistor junction 138. Unidirectional voltages across the resistors 137 are. balanced when the component of voltage in the winding 124 or 131 in phase or 180 out of phase with that in the winding 136 falls to zero. Such voltage, however, falls to zero only when the rotors 118 and 124'are' electrically degrees apart. For other positions, the magnitude and phase of the voltages induced in the windings 124 and 131 depend on the angular position of the rotor 124. Accordingly, the phase sensitive amplifier 126 produces a direct current output only when the rotor 124 deviates from a position corresponding to that of the rotor 118, and in case of any deviation the strength of the voltage at the output conductors 127 varies in amplitude with the amount of the deviation and in polarity with thedirection of the deviation.

For introducing a secant correction, the mechanism 54 is provided with a cosine cam 141 which has a liftvarying axially in accordance with the cosine function and varying angularly from a predetermined radius in accordance with the angular rotation of the cam 141.

The axial length of the cam 141, as shown, represents less than 90 degrees variation in gun elevation. For rotating the cam 141, a direct current motorv 142 is provided, which is energized by the phase-sensitive amplifier output conductors 127, and is mechanically connected to the cam 141 through a bevel gear 143 and a pinion and gearing 144. For moving the three-dimensional cam 141 axially, a rack and pinion gearing 145 is provided which is driven through a shaft 146 and'a bevel gear- 147 from the gun elevation shaft 58. Cooperating with the cam 141 is a toothed cam follower 141a, meshing with a pinion 1411) to the shaft 125 for causing the rotor 124 to rotate in response to variations in cam lift.

The slant plane correction mechanism 54 is also provided with an output shaft 148 driven bythe direct current motor 142 through the gearing 143 and having an angular position corresponding to the angular position of the three-dimensional cam 141. The arrangement is such that the angular motion of the shaft 148 is proportional to the angular motion of the shaft 125 multiplied by the secant of the angle of rotation of the elevation shaft 58.

When the cosine cam 141 is in the axial position with the small end engaging the cam follower 141a (corresponding to nearly 90 gun elevation), the radius of the cam varies very little with angle. On the other hand, as the cam is moved toward the positionwith the large'end engaging the cam follower, representing zero degrees gun elevation, the radius of. the cam-varies considerably with angle. In the former case, the motor 142 must rotate the cam 141 through a large angle to maintain the rotor 124 in its zero-voltage position as the transmitter rotor 118 turns, whereas in the latter case the motor 142 must rotate the cam 141 through a relatively small angle to maintain its rotor 124 in its zero voltage position as the transmitter rotor 118 turns. Consequently, the factor introduced into the motor of the shaft 148 is inversely proportional to the function of the cam 141. Thus a secant factor results. Since the shaft 125 reproduces the azimuth correction angle of the shaft 69, the angular position of the shaft 148 represents this correction angle compensated by a factor equalling the secant of elevation angle for use in connection with the scanner control mechanism 25.

A differential 149 is provided for combining the correction angle appearing at the shaft 148'with the azimuth gun position angle of the shaft 57 to provide an angular position of an output shaft 151 of the differential 149 which represents the hypothetical line of sight of the target in azimuth. For comparing this angular position with that of the radio scanner mechanism 25, a remote electrical transmission system is provided similar to the system 55117 previously described. In this case there is a transmitter 152 similar in construction to the transmitter 55 previously described at one end of the conductors 27 and a receiver 153 similar in construc- 155' is provided which produces a reversible unidirec- .servo mechanism the shafts 151 and 49. One of the devices 152 and 153 is mechanically connected to either the shaft 151 or the shaft 49, and the other of the devices 152 and 153 is connected to either the shaft 49 or the shaft 151.

For transmitting an angular indication of the position of the elevation correction shaft 67 to a shaft 157, an electrical transmission system is provided comprising the pick-off transmitter 56 and a receiver 158 corresponding to the devices 55 and 117, respectively, and a is provided comprising a phasesensitive amplifier 159 similar to the device 126, and a direct current motor 161 energized by the direct current output of the phase-sensitive amplifier 159 and rotating the rotor shaft 162 of the receiver 158 as well as the shaft 157.

For combining the elevation prediction angle represented by the position of the shaft 157 with the elevation gun position represented by a shaft 163 geared to the elevation shaft 58, a differential 164 is provided having an output shaft 165. The angular position of the output shaft 165 is electrically transmitted through conductors 28 by means of a transmitter 166 corresponding to the transmitters 55 and 152 and a receiver 167 corresponding to the receivers 117 and 153. Likewise, a phase-sensitive amplifier 168 is provided having an input connection from the receiver 167 and a pair of output conductors 169. The relative positions of the devices 166 and 167 may, however, be interchanged.

The output terminals 156 and 169 of the phase-sensitive amplifiers 165 and 168 are connected to the input terminals of the deviation indicator 23 for enabling a gunner to determine whether or not there is any deviation between the hypothetical line of sight set into the shafts 151 and 163 by the computing mechanism and the actual radio line of sight determined by the tracker 25.

It will be seen that the indicator 23 is operatively connected with the outputs of differentials 149 and 164 and with the azimuth and elevation shafts 49 and 51 of the tracker, thus forming a common means or a means common to said differentials and said tracker shafts and operated by all to provide an indication of deviation in azimuth and elevation between the computed present target position and the line of sight of the tracker.

The specific construction of the deviation indicator 23 is not my invention and my invention is not limited to any specific type of indicator such as a cathode ray tube device or a crossed-pointer instrument. Nevertheless, the latter type of indicator lends itself well in a local turret, where space is at a premium. It may take the form, for example, of a pair of deflecting-pointer center-zero galvanometers mounted in a common casing, with one pointer vertical and the other horizontal when zero current flows in each of the input connections 156 and 169.

\Vhen the gunner wishes to track the target optically, this is done in the conventional manner by observing the target along the optical line of sight 64 and manipulating the hand controls 21 (Fig. 2) until the image of the target and the image of the reticle coincide in the observers eye.

When the target is to be tracked by radio, the scanner is caused to locate and thereafter automatically to track the target by the operator who has charge of this mechanism, and the gunner then observes the deviation indicator 23 in order to determine whether or not the computed line of sight agrees with the radio line of sight. The operator manipulates the control handles 21 as in the case of the optical line of sight to effect rotation of the turret and elevation of the gun until zero indications for both azimuth and elevation are obtained from the deviation indicator 23.

If the scanner is provided with control and driving means of sufficient power, and the computer mechanism is made with sufficient strength, it is also possible to operate the apparatus as an automatic remote-turret gun-director system instead of a local turret system, by substituting positive transmissions between the shafts 51 and 151 and between the shafts 49 and 165-for the comparison circuits shown, in order to correlate corresponding shafts of the computer and the tracker.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing fromthe scope thereof, it is intended that all T8 matter, contained in the above descriptionv or shown in the accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:

l. A radio lead sight comprising a lead computer having azimuth and elevation position input shafts settable according to the position of a gun, a range input shaft, and azimuth and elevation correction angle output shafts, radio attachment apparatus for the computer, a radio tracker and a deviation indicator, said radio tracker comprising means for tracking a target by means of radio waves and producing rotary shaft indications of angular position in elevation and azimuth and an electrical indication of range, said attachment apparatus comprising an electromechanical converter for rotating the range shaft of the computer in accordance with electrical indications of range, a differential for combining correction angle with movement of the elevation angle iuputshaft, a secant factor compensating device for converting correction angle in azimuth slant plane to correction angle in azimuth horizontal plane, and a differential forcombining correction angle in a horizontal plane with movement of the azimuth angle input shaft, and said deviation indicator comprising a common means having an input operatively connected with the outputs of. said differentials and with the azimuth and elevation shafts of the tracker for indicating the amount of deviation between the angular position of the outputs of the differentials and the azimuth and elevation shafts of the tracker.

2. A radio lead sight comprising a radio tracker defining a line of sight for following a target, a lead computer, correction attachments for said lead computer, and common comparison means between said computer and said radio tracker, said radio tracker comprising an output shaft with means to rotate it for representing angular position of a target, said lead computer comprising input shaft means settable according to the position of a gun, and output shaft means representing a proper lead correction angle, said correction attachment comprising differential means for combining movement of said input shaft means with the lead correction angle, and means for correcting for the difference between correction in a slant plane and horizontal plane correction of a radio line of sight, said common comparison means comprising connections with the output of said differential and with said tracker shafts for comparing the output of said differential with the angular position of said tracker shaft.

3. A radio lead sight comprising, a radio tracker defining a line of sight for following a target, a lead computer, correction attachments for said lead computer, and common comparison means between said computer and said radio tracker, said radio tracker comprising first output means representing angular position of the target and second output means representing range of a target, said lead computer comprising input shaft means settable according to the position of a gun, and output shaft means representing a proper, lead correction angle, said correction attachment comprising means for supplying the range output of said radio tracker to said range input shaft, differential means for combining movement of said input shaft means with lead correction angle, and means for correcting for the difference between correction in a slant plane and horizontal plane correction for radio line of sight, said common comparison means comprising connections with the output of said differential means and with said first output means of the tracker for comparing theoutput of said differential with the angular position output of said tracker.

4. A radio lead sight comprising, a radio tracker defining a line of sight for following a target, a lead computer, correction attachments for said lead computer, and common comparison means between said computer and said radio tracker, said radio tracker comprising first output means representing angular position of a target and second output means representing range of a target, said lead computer comprising input shaft means settable according to the position of a gun, and output shaft means representing a proper lead correction angle, said correction attachment comprising means for supplying the range output of said radio tracker to said range input shaft, and differential means for combining movement of said input shaft means with lead correction angle, said common comparison means comprising connections with the output of said differential means and said first output means of the tracker for comparing the output of said differential with the angular position output of said tracker.

S. A radio lead sight comprising, a radio tracker defining a line of sight for following a target, a lead computer, correction attachments for said lead computer, and common comparison means between said computer and said radio tracker, said radio tracker comprising output shafts for representing angular position of a target in azimuth and elevation respectively, said lead computer comprising a pair of input shafts settable according to the position of a gun in azimuth and elevation, a pair of output shafts representing a proper lead correction angle, said correction attachments comprising differential means for combining movement of the azimuth input shaft with lead correction angle in azimuth, second differential means for combining movement of the elevation input shaft with correction lead angle in elevation, and means for correcting for the difference between correction in a slant plane and horizontal plane correction of a radio line of sight, said last means being interposed between said azimuth correction angle shaft and the output of said azimuth differential, said common comparison means comprising connections with the outputs of said differential means and the output shafts of said tracker for comparing the outputs of said azimuth and elevation differentials respectively with the angular positions of said azimuth and elevation tracker shafts.

6. In an optical computing sight having input shafts settable according to the azimuth and elevation position of a gun and azimuth and elevation correction angle shafts, said attachment comprising a secant factor mechanism for converting slant plane correction angle into horizontal plane correction angle, an azimuth differential having a pair of input shafts and an output shaft, one of said input shafts being driven by said azimuth input shaft, said secant correction device being interposed between said azimuth correction angle shaft and said second input shaft to the differential, the output shaft of the differential representing the present angular position in azimuth of a target in proper alignment to be struck by the gun, and said elevation differential having an input shaft driven by said elevation input position shaft, a second shaft driven by said elevation correction shaft, and an output shaft representing present position in elevation of a target.

7. A radio line of sight attachment for an optical computing gun sight comprising in combination with position shaft means of a computing sight settable according to the position of a gun and lead angle correction shaft means of the computing sight, a differential means for combining angular positions of said shafts to produce an output representing the angular position of the hypothetical present position of the target, a radio tracker having a shaft representing actual present position of a target, and a common deviation indicator operatively connected with said differential means and with the shaft of said tracker for comparing and indicating the difference between the angular positions of said hypothetical present position shaft and said actual present position shaft for enabling a gunner to correct the gun position.

8. A director comprising a tracker for following a target, a computer, correction attachments, and common correlating means between said tracker and said computer, said tracker comprising means for producing an output representing angular position of a target, said computer comprising input means settable according to the position of a gun and means for producing an output representing a lead correction for the proper line of sight, said correction attachment comprising means for combining input position with correction to represent a line of sight, and said, correlating means being connected with said correction attachment and the output of said tracker to correlate the representation of a line of sight with the tracker output and thereby measure the amount of deviation therebetween.

9. A radio lead sight comprising a radio tracker defining a line of sight for following a target, a lead angle computer having an input member settable according to the angular position of a gun and mechanism actuated by said member for operating an output device according to a proper lead angle, differential means coupled to said input member and said output device for algebraically adding the angularposition of the gun and the computed lead angle to provide a measure of the computed present target position, and common indicating means connected to said differential means and said tracker in a manner to indicate the deviation between the position of the line of sight of said tracker and said computed present target position.

10. A radio lead sight comprising a radio tracker defining a line of sight for following a target, a lead angle computer having an input member settable according to the angular position of a gun and mechanism actuated by said member for operating an output device according to a proper lead angle, differential means coupled to said input member and said output device for algebraically adding the angular position of the gun and the computed lead angle to provide a measure of the computed present target position in azimuth and elevation, and a pair of common indicating means each thereof being operatively connected with said diflferential means and With said tracker to provide respectively an indication of deviation in azimuth and elevation between the computed present target position and the line of sight of said tracker.

11. A radio lead sight comprising a radio tracker defining a line of sight for following a target, a lead angle computer having an input member settable according to the angular position of a gun and mechanism actuated by said member for operating an output device according to a proper lead angle, differential means coupled to said input member and said output device for algebraically adding the angular position of the gun and the computed lead angle to provide a measure of the computed present target position in azimuth, and a common means operatively connected with said differential means and with said tracker for control thereby to provide a measure of deviation between the azimuth position of the line of sight of the tracker and the computed present target position in azimuth.

12. A radio lead sight comprising a radio tracker defining a line of sight for following a target, a lead angle computer having an input member settable according to the angular position of a gun and mechanism actuated by said member for operating an output device according to a proper lead angle, differential means coupled to said input member and said output device for algebraically adding the angular position of the gun and the computed lead angle to provide a measure of the computed present target position in elevation, and a common means operatively connected with said differential means and with said tracker for control thereby to provide a measure of deviation between the position of the line of sight of the tracker in elevation and the computed present target position in elevation.

Gray Apr. 24, 1923 Watson Dec. 20, 1932 

